The present disclosure relates to using spot beam overlap for geolocation. In particular, it relates to using spot beams to obtain precise positioning that maintains a high enough accuracy to be used for time transfer. Specifically, the spot beams utilize at least one acquisition signal, which is used for assisting in geolocation.
Currently, navigation and timing signals provided by various existing satellite navigation systems often do not provide satisfactory system performance. In particular, the signal power and bandwidth of such navigation and timing signals are generally insufficient to meet the needs of many demanding usage scenarios. For example, existing navigation and timing approaches based on global positioning system (GPS) signals may not typically be available to a navigation user in many instances. During operation, a GPS receiver must typically receive at least four simultaneous ranging sources in order to permit three-dimensional (3D) positioning and accurate time transfer. However, GPS signals often provide insufficient, low-signal power or geometry to readily penetrate urban canyons or walls of buildings. When this occurs, a GPS receiver will not be able to receive the signals it requires for accurate 3D positioning and time transfer. In another example, navigational approaches based on cellular telephone or television signals also do not provide satisfactory system performance. This is because their signals typically lack vertical navigation information, which is desired for many navigational usage scenarios.
Existing navigation systems have attempted to address indoor navigation deficiencies by the use of various approaches. Some of these various approaches include the use of inertial navigation systems, specialized beacons, and highly sensitive GPS systems. However, it should be noted that each of these approaches has their own unique drawbacks. Inertial navigation systems drift and can be expensive. Beacons require specialized fixed assets that need to be surveyed, can be expensive, and are not standardized. As such, beacons are built to only have a specialized utility. And, sensitive GPS systems often do not perform to user expectations due to the weakness of the GPS signals in indoor environments. The disclosed systems and methods are able to provide an improvement in navigation system performance when the user receiver device is located in an attenuated environment, a jammed environment, and/or an occluded environment, such as indoors.